With development of storage technologies, people impose a higher requirement on a capacity and performance of a storage system, but a storage system with a large capacity and high performance is expensive. To meet, with a low price, performance and capacity requirements of the storage system, a hierarchical storage technology emerges.
A hierarchical storage technology of data is a mainstream technology that responds to a data lifecycle management requirement, and parameter values such as a data access frequency and an IO count may be recorded by monitoring service data. In a storage system, a tier at which the service data should be stored may be decided according to the monitored parameter values such as IO, where hot data may be migrated to a high performance tier in the storage system, and cold data may be migrated to a low performance tier in the storage system. Therefore, the performance and capacity requirements of the storage system may be met with a relatively low price.
The hierarchical storage technology mainly includes three parts: data monitoring, cold and hot data identification, and data migration. In the prior art, a data monitoring function module, a cold and hot data identification function module, and a data migration function module are distributed on storage nodes in a storage system, but the entire storage system has no uniform cold and hot identification criterion. Therefore, a hierarchical storage function can be implemented only on a single storage node in the storage system, and data cannot be migrated across storage nodes, which drastically reduces practicality and availability of the hierarchical storage function of the storage system.